Piston



Dec. 8, 1931. F. JARDINE ET AL 1,835,875

PISTON Filed March 10, 1927 Y- Q 4 ATTORNEYS Patented Dec. 8, 1931 UNITED STATES ass-sen Y PATENT OFFICE FRANK JARDINE AND .TAIVJIES J. COOPER, 0F CLEVELAND, OHIO, ASSIGNORS, BY MESNE ASSIGNMENTS, TO THE CLEVELAND TRUST COMPANY, OF CLEVELAND, OHIO, A

CORPORATION OF OHIO, AS TRUSTEE rrsron Original application filed January 7, 1926, Serial No. 79,800. Divided and this application filed March 10,

' 1927. Serial No. 174,202.

This invention relates to pistons for internal combustion engines or the like, and more particularly to pistons made of some metal having a relatively high co-efiicient of expansion such as aluminum or aluminum alloy,or the like,to be used in a cylinder made of a material having a relatively low coeiiicient of expansion such as cast iron or the like.

It is well known that such pistons possess many desirable qualities such as lightness, high heat conductivity and the like, but since the co-eficient of expansion due to heat of such materials differs from that of the cylinders in which they operate, difiiculties and disadvantages are encountered at various temperatures, for example, pistons that will not slap when cold will stick when hot, and vice versa.

The principal object of our invention is to provide a piston made of aluminum, aluminum alloy, or the like, which can be fitted with a very small clearance when installed and which clearance will be substantially maintained throughout the temperature ranges met in practice, without slapping, binding or scoring of the cylinder or undue wear on the piston itself.

These and other objects of our invention as well as the invention itself will be better understoodfrom a description of one or more structures embodying the invention.

This application is a division of our application Serial No. 79,800, filed January 7 1926,and embodies the subject matter claimed broadly in the co-pending application of Frank Jardine, Serial No. 47,214, filed July 31, 1925.

In the drawings forming a part of this specification- Fig. 1 is a side elevation of a piston embodying our invention;

Fig. 2 is a section thereof along the line 22 of Fig. 1;

Fig. 3 is a bottom plan view thereof; Fig. 4 is an elevation of the member A hereinafter to be particularly described.

We will refer to the preferred embodiment in which the head of the piston is shown at 9 and consists of the top 10 and side walls 11 grooved at 12 for the piston rings. The walls 11 are shown as cylindrical. As many grooves 12 as desired may be used. The piston skirt is shown generally at 13 and comprises thrust or Wear face parts 14 and 15.

The parts 14 and 15 areseparated from the head by air gaps 16 and 16 here shown as horizontal slots out between the side wall of the head 11 and the parts 14 and 15 and running parallel to the grooves 12. The piston is provided with bosses 17 and 18 for the wrist pin. These bosses are located in alignment and diametrically opposite one another in the piston. The bosses are connected to the head by members, here shown as webs 19, 20, 21 and another like 20, but not illustrated in the drawings. These webs are parallel with the wrist pin axis and serve to make the piston stauncher as well as to connect the bosses to the head. The bosses should be, and are best, connected so that the head, skirt and bosses are integral and of the sameinaterial as the bottom of the skirt. In the embodiments shown, this is accomplished by the webs 22 and 23 which are connected to the under sides of the bosses and to the inner sides of the skirt through members 24 and 25 here shown as culvertshaped and hereinafter called culverts. The piston head is preferably strengthened by webs 26. The skirt is cutaway as shown at 27 and 28 about the bosses 17 and 18 and the bosses are set within the perimeter of the piston to permit expansion along the axis of the wrist pins without binding or scoring.

The piston skirt is best made continuous below the openings 27 and 28. In the embodiment shown, strap-like members 29 and 30 connect the parts 14 and 15 at the bottom. The member 29 is slitted along the long axis of the piston at 31 and the member 30 is slitted likewise at 32. These slits are preferably slanting to the long axis of the piston and are spanned by the culverts 24 and 25 which are of resilient material. The

piston skirt thrust parts 14 and 15 are connected together by members of a material" ulate the expansion of the skirt to maintain loothe expansion thereof constant with the expansion of the engine cylinder, or so nearly thereto, that though there is very little clearance at-the time the pistons are installed,

such clearance is substantially maintained and there will beno slap, no sticking and no scoring or undue wear.

In the embodiment shown, strips of the desired material are used to interconnect the parts of the skirt. These strips are anchored in the parts they connect. It is convenient to use such members as A, (Fig. 4)'which are best made of iron, steel or other suitable material and which consist of the lateral members 33 and 34 and the vertical members 35 and 36 provided with catches 37. To securely connect the members 33 and 34 to the skirt parts the vertical members 36 may be buried in the part 14, for example,

by embedding them in buttresses formed on the inside of the part 14, thus securely anchoring the ends of the lateral members 33 and 34 in the part 14. The other ends of the members 33 and 34 are as securely anchored in the face part 15 in much the same manner. The vertical members 35 are buried in the buttresses 39 formed on the inner walls of the part 15 of the piston skirt. The bosses 17 and 18 and webs 19, 20 and 21 are opened at 40 and 41 and 42 and 43, respectively, to permit the mounting of the members 33 and 34 in the skirt. As will be seen the members 33 and 34 are arranged chordally in the piston.

By connecting the piston skirt thrust face parts together with both iron and aluminum,

we avoid slapping at the high temperatures and danger of cooking of the members 14 and 15 out of normal due to unequal heating and consequent expansion at the top and bottom of the skirt. The members 33 and 34 are usually and best made of low expansion steel, which has a lower co-eflicient of heat expansion than cast iron so that the castiron cylinder will expand away from the piston and slapping will occur at high instead of low temperatures. By maintainirjlg the aluminum connection circumferentia y this is avoided, since the more rapidly expanding aluminum will compensate for the under expansion of the steel members with the result that the net expansion will be substantially that of the cast iron cylinder.

There will also be no danger of the member 15 cocking out of line since the more rapidly expanding aluminum-steel combina tion at the bottom will compensate for lower temperatures there. Nor will there be danger of binding at the bottom of the piston skirt when thecircumference of the skirt vis complete, since the slits 31 and 32 perculverts expand giving the required expansion perpendicular to the wrist pin axis, circumferential expansion of the culverts will bring the culvert ends toward each other and thus tuck in the ends of the strap-like members 29 and 30 so they will not project out radially and injure the cylinder walls. The lower parts of the skirts may be thinned or relieved at 50.

The operation is as follows: The piston is fitted with very little or almost no clearance. As the piston heats, the bosses tend tomove outward, for which movement there is ample allowance. The expansion in the other direction will be the resultant expansion of the members 33, 34, 24 and 25, plus, of course, that of the thrust faces, and these parts are so regulated that the piston walls will follow the cylinder walls with fidelity.

Contraction will be in reverse of expansion.

The term aluminum as used herein includes aluminum alloys.

While we have illustrated and described these embodiments of our invention and these particular details, we wish to be limited vided with diametrically opposite thrust faces and being provided with substantially rectangular diametrically opposite openings at right angles to the thrust faces, said open ings extending from adjacent the head and terminating well before reaching the lower part of the skirt, piston pin bosses located centrally within said openin s, connecting columns in said openings set back from the cylindrical surface of the piston and joining the lower edge of the side wall of the piston head, the pin bosses and the portion of the skirt below the openings, the portions of the skirt below the openings being provided with slightly inclined slits which run from the lowermost edge of the piston to the opening without cutting the columns, steel struts joining the thrust faces and said columns, said pistons having horizontal slits which disconnect the thrust faces from the head of the piston and which slits pass from one of said rectangularly shaped openings to the other leaving the columns to connect the skirt to the head.

2. In a piston made of a material having a relatively high coefficient of expansion, the combination of a head and a skirt provided with thrust faces, the portions of the skirt at right angles to the thrust faces being cut away part way down, piston pin bosses in said cut away skirt portions, columns indented in said cut away portions and joining the bosses, the head and the portions of the skirt below the cut away portions, the portions of the skirt below the cut away portions being provided with slits running in a vertical direction and joining the lower end of the piston skirt to the cut away portions and terminating in front of said columns, and struts of a material having a higher co-efiicient of expansion than the head and body of the skirt joining the thrust faces and the connecting columns.

3. In a piston for internal combustion engines or the like, the combination of a head consisting of a top and a depending cylindrical shaped flange grooved on the outside for piston rings, a skirt for the piston comprising portions having thrust faces adapted to engage the walls of'the cylinder of the engine when the piston is mounted therein,

said skirt bein generally cylindrical in shape and said skirt and head being made of a material having a relatively high co-efiicient of expansion, diametrically oppositely placed wrist pin bosses mounted in said skirt and having their outer ends within the periphery of the skirt, means connecting said wrist pin bosses .with the head, the skirt being relieved or cut away about the bosses from the lower part of the head to below the bosses and leaving the lower portion of the piston connected together circumferentially, the lower portions of the piston being slit below the bosses, the diametrically opposite thrust face portions being disconnected from the head by arcuate slots at the top of said thrust face portion, connectors made ofa material of a relatively lower co-efficient of expansion-v than the material of the piston anchored at either end in the thrust faces and connected to the bosses in the central portions thereof one of said connectors being located above each boss and each extending on a chord across the interior of the piston and perpendicular or substantially perpendicular to the wrist pin axis.

4. In a piston for internal combustion engines or the like, the combination of a head consisting of a top and a depending 'cylin- 'drical shaped flange grooved on the outside for the piston rings, a skirt for the piston comprising portions having thrust faces adapted to engage the walls of the cylinder of the engine when the piston is used therein, said skirt being generally cylindrical in shape and said skirt and head being made of a material having a relatively high co-eflicient of expansion, said skirt being provided with two substantially rectangular openings passing clear through the walls of the skirt placed diametrically opposite to each other and at substantially right angles to the thrust faces, diametrically oppositely placed wrist pin bosses mounted in the openings in said skirt,

columns within the outer periphery of the skirt extending through the central part of the openings and connecting the head of the piston, the piston pin bosses and the portions diametrically opposite thrust face portions being disconnected from the head by arcuate slots at the top of said thrust face portions, and struts of a lower co-eflicient of expansion than the material of which the piston is made connecting the thrust faces and said columns within the perimeter of the piston and located between the head and the bottom of the boss openings.

5. In an aluminum alloy piston for internal combustion engines or the like, the combination of a head consisting of a. top and a depending cylindrical shaped flange grooved on the outside for thepiston rings, a skirt for the piston comprising portions having opposite thrust faces adapted to engagethe walls of the cylinder of the engine when the piston is used therein, said skirt being generally cylindrical in shape, said skirt being provided with two substantially rectangular openings passing clear through the walls of the skirt placed diametrically opposite to each other and at substantially right angles to the thrust faces and extending part way the length of the skirt, diametrically oppositely placed wrist pin bosses mounted in the openings in said skirt, columns within the outer periphery of the skirt extending vertically along the central parts of the openings and connecting the head of the piston, the piston pin bosses and the portions of the skirt below the substantially rectangular openings, eachcolumn including a web having a portion substantially perpendicular to the axis of the wrist pin and a web at right angles thereto between the boss and the head, thev top of the portions of the skirt below the openings forming a'ledge in front of the columns, inclined vertically extending slits passing clear through the central lower portions of the skirt from the bottom edge of the skirt to and extending through said ledges abreast of but without int-:rsecting the columns, the diametrically opposite thrust face portions being disconnected from the head by arcuate slots at the top of said thrust face portions, and the sole connection between the connecting columns.

a relatively, high co-efiicient of expansion the combinatioir'of a head and a skirt provided with thrust faces portions of the skirt at right angles to the thrust faces being cut away part way down, piston pin bosses in said cut away skirt portions, columns indented in said cut away portions and joining the bosses, the head and the portions of the skirt below the cut away portions, the portions of the skirt below the cut away portions being provided with slits running in a vertical direction and extending from the lower end of the piston skirt to the cut awaj' portions and terminating in front! of said columns, and struts of a material having a higher co-eflicient of expansion than the head and body.

the thrust faces and the of the skirt joining In testimony whereof we hereunto aifix our signatures this 5th day of March, 1927.

FRANK JARDINE. JAS. J. COOPER. 

